A new record of the diogenid hermit crab Dardanus callichela Cook 1989 is described from the Visayan Sea, Central Philippines. Four specimens of D. callichela were caught in fish traps deployed at depths of about 30–40 m adjacent to islands to the north (Nagarao Island, Masbate) and south (Baliguian Island, Iloilo) of the Visayan Sea. The morphological description and colour photographs are provided. Partial sequences of the cytochrome oxidase subunit I (COI) are provided for two specimens and deposited in GenBank. This new record brings the total number of known Dardanus in the Philippines to 16 species.

This study characterized shell occupation by two species of hermit crabs and analysed the occurrence of ectosymbionts on their shells, in a comparative way. The hermit crabs Clibanarius antillensis and Calcinus tibicen were selected for this comparative study because of their abundance and wide distributions. Specimens were collected manually during spring low tides every 2 months, from February 2011 to January 2012 in north-eastern Brazil (03°S), and in south-eastern Brazil (23°S). The populations showed different patterns of shell occupation and ectosymbiont coverage. The plasticity of these ecological traits is discussed in a broad context and possibly correlated to habitat differences.

The larval development of the hermit crab Areopaguristes nigroapiculus (Komai, 2009) (Decapoda: Anomura: Diogenidae) is described and illustrated from the material reared in the laboratory. The development included three zoeal and a single megalopal stages. At 22–25°C, megalop of A. nigroapiculus was attained 6–9 days after hatching. The present paper is the first description of the complete larval development in the genus Areopaguristes. Morphological characters of zoeas and megalop of A. nigroapiculus are compared with those described for the closely related Paguristes species. The comparison on the zoeal characters revealed that A. nigroapiculus is distinguished from Paguristes species by the absence of anterolateral carapace spines and by the fused fourth telson process in zoea III. These two features are possible generic characters of Areopaguristes. In the rest of larval characters, A. nigroapiculus agree well with Paguristes species having three zoeal stages. In the plankton of Peter the Great Bay, the larvae of A. nigroapiculus sporadically occurred only in July and August, at depths of 3–45 m and surface water temperatures of 18–22°C.